Means for protecting resistors in electric furnaces



May 1 1923. 1 45x399 G. M. LITTLE MEANS FOR PROTECTING RESISTORS IN ELECTRIC FURNACES Filed April 25, 1921 WITNESSES: INVENTOR 2,2 1). wil Georye/ZLiIf/e.

. W BY ATTORNEY UNITED STATES PATENT OFFICE.

GEORGE E. LITTLE, OI PITTSBURGH,

ELECTRIC & MANUFACTURING PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE COMPANY, A. CORPORATION OF PENNSYLVANIA.

MEANS FOR PROTECTING BESISTOBS IN ELECTRIC FURNACES.

Application filed April 25, 1921. Serial No. 484,290.

To all whom it may concern:

Be it known that I, GEORGE M. LITTLE, a citizen of the United States, and a resident of Pittsburgh "in the count of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Means for Protecting Resistors in Electric Furnaces,

' of which the following is aspecification.

My invention relates to electric furnaces and particularly to electric-resistance furnaces and it has for its object to provide a means for effectively protecting carbonaceous resistors of electric furnaces against the oxidizing effect of enteringair.

In high-temperature furnaces of the type disclosed in my application Serial 0. 454,776, filed March 23, 1921, it is very desirable to protect-the carbonaceous resistor against the oxidizing effect of air entering the furnace during the ordinary operation thereof.

In practicing my invention, I provide a cam-actuated and spring-operated plunger pump which is operated to forcibly in ject predetermined quantities of an inflam mable oil into the furnace chamber at a point of entry and at such velocity as to prevent the oil being volatilized until it has reached substantially the center of the furnace chamber. It is volatilized by the heat of the furnace walls and of the resistor itself and causes a sooty vapor to be generated which is caused to deposit its soot on the outer surface of the resistor and on the inner surface of the furnace walls. A suitable container is provided for holding a supply of oil which is fed to the plunger pump by gravity.

The single figure of the drawing isa view, in vertical section of a furnace embodying my invention.

An electric resistance furnace 1 comprises an outer metallic casing or framework 2 and a plurality of supporting members 3. An outer layer of heat-insulating material 4 comprises a plurality of bricks or blocks located inside of the framework 2. An inner layer 5 of hightemperature-resisting material is located inside of the outer layer 4 and comprises a plurality of bricks or blocks suitably spaced apart to form a furnace chamber 6. v

A resistor 7 is located in the furnace chamber 6 and comprises a plurality of carbonaceous resistor elements, substantially as described in the hereinbefore mentioned application.

An opening 8 is tprovided at substantially the bottom of the urnace chamber through whlch metallic objects may be inserted into the furnace chamber 6 to be heated by the resistor 7 when it is traversed by a suitable electric current.

The opening 8 permits a certain amount of air to enter the furnace chamber, and there is always some leakage through linings 4 and 5. This entering air oxidizes the carbonaccous resistor when the same is being operated at a relatively high temperature and would soon cause serious deterioration thereof if no protecting means were employed.

I have found that a deposit of soot on the outer surface of the resistor 7 effectively prevents the resistor from being attacked by the incoming air and means are therefore provided to generate a sooty vapor in the furnace chamber.

A container 9 of any suitable dimensions and material is mounted at the side or rear of the furnace on a bracket member 10 suitably secured against the metal casing 2. A depending tube 11 and an adjustable valve member 12 permit of directing a flow of inflammable oil from the container 9 to a pump 13.

The pump 13 comprises a cylindrical tube i l, a plunger 15, reciprocally movable therein and actuated by a pivotally mounted lever 16 that is connected to link 17. The lever 16 may be pivotally mounted at 18 on a suitable bracket 19 that is secured to the metallic casing 2 of the furnace. The oil from the tube 11 drops into a member 20 of funnel shape that is connected to the tubular member 14. her 21 is provided to hold the lever in such position that the plunger 15 is in its inner position in the cylinder 1 1, in which position any oil located in the funnel 20 is precluded from flowing into the cylinder 14.

Means for intermittently moving the lever 16 comprise a continuously driven pulley 22 suitably mounted on the bracket 19 and a cam member 23 suitably connected to be operated by the pulley 22. The pulley 22 the plunger 15 by a A spring memsuch as an electric motor (not shown), and

the cam member 23 is operatedto move the plunger outwardly in the cylinder 14,

thus permitting a redetermmed quantity of oil to flow into t e cylinder 14 ahead of 6 the plunger 15. It is assumed that the pulle 22 and the cam 23 are rotated in a clockwise direction. In the position indicated in the drawing, the plunger 15 has been moved outwardly in the cylinder 14 to its farthest position and, upon further movement of the cam 23, the sprlng 21 suddenly and forcibly moves the lever 16 and the plunger 15 to force the oil through a nozzle 24 at the inner end of the cylinder 14 into the furna-"c chamber. The pump 13 is mounted so that the nozzle 24 of the cylinder 14 is located in a conduit 25 that extends through the rear wall at an angle to the floor of the furnace.

The amount of oil which is thus caused to be forcibly injected into the furnace chamber 6 at predetermined time intervals is sufliciently large to be rojected into substantially the center of t e furnace chamber 25 before being volatilized by the high temperature existing in the chamber. The angle at which the oil is injected into the furnace chamber is so selected that, in combination with the oint of entry. the velocity, and quantity of the oil, the above mentioned result is obtained.

Since a small portion of the stream of oil intermittently injected into the furnace chamber may be volatili'zed while still in the conduit 25 and cause a deposit of soot on its walls, means are provided for permit ting a small quantity of air to enter continuously into the opening 25 to combine with and burn out such sooty deposits therein. A relatively small opening 26, which may be adjustable, if desired, is provided in the metal supporting wall of the cylinder 14 to permit a small quantity of air to flow into the conduit 25 and burn away any sooty deposit, between the intermittent injections of oil made by the pump 13.

It may be noted that the device embodying my invention provides a means for introducing a hydro-carbonaceous fluid into the heated chamber of an electric-resistance furnace, the fluid being injected into the chamber from such point, at such velocity, in such quantity and in such a direction as to permit of substantially all of the fluid reaching the center thereof before being volatilized or cracked by the heat. of the furnace. When the oil volatilizes, a substantially even deposit of soot is caused to be made, not only on the resistor but also on the inner surface of the walls of the furnace, thus protectin the resistor against the oxidizing effect 0 entering air and also sealing any cracks or openings which may appear in the furnace walls to prevent leaking of the heated gases in the furnace through the furnace walls and to reduce the amount of entering air to a minimum.

The device embodying my invention provides a simple means for preventing the clogging of the pump or of the opening in wh1ch the pum is located, thus insuring a continuit of t e furnace itself and of its associate mechanism.

Various modifications may be made in the device embod ing my invention withoutdeparting from the spirit and scope thereof and I desire that only such limitations shall be placed thereon as are imposed by the prior art or are specifically set forth in the appended claims.

1 claim as my invention:

1. In an electricu'esistance furna'e, the combination with a furnace chamber and a carbonaceous resistor in said chamber, of means for introducing a hydrocarbonaceous fluid into said chamber, said means comprising a plunger pump.

2. An electric-resistance furnace, comprising a carbonaceous resistor and means for enveloping said resistor with a hydrocarbonaceous vapor, said means comprising a plunger pump.

3. In an electric-resistance furnace, the combination with a furnace chamber and a carbonaceous resistor therein, of means for introducing a hydrocarbonaceous fluid into said chamber under pressure, said means comprising a cam and spring operated plunger pump.

4. In an electric-resistance furnace, the combination with a furnace chamber and a carbonaceous resistor in said chamber, of means for intermittently spraying a hydrocarbonaceous fluid into said chamber and for distributing it uniformly throughout the furnace chamber.

5.In an electric-resistance furnace, the combination with a furnace chamber and a carbonaceous resistor in said chamber, of means for introducing a hydrocarbonaceous fluid into said chamber, said means comprising a cam-actuated plunger pump.

6. In an electric-resistance furnace, the combination with a furnace chamber and a carbonaceous resistor therein, of means for intermittently introducing a hydrocarbonaceous fluid into said chamber under pressure, said means comprising a cam-andspring-operated plunger pump.

7. The method of protecting a carbonaceous resistor, located in a furnace chamber, against oxidation which comprises introducing a hydrocarbonaceous fluid intermittently into, and distributing the same in, said chamber by pressure-actuated means adapted to distribute the same uniformly throu hout the furnace.

8. 11 an electric-resistance furnace, the combination with walls spaced apart to form a furnace chamber, one of said walls having a conduit therein near the bottom of said chamber, and a carbonaceous resistor located in the upper part of said chamber, of means for causing carbon to be deposited on said resistor and said furnace walls, said means comprising a plunger pump for intermittently forcing a hydrocarbon oil through said wall conduit, and means for permitting air to enter said conduit for removing any carbon deposited on its walls.

9. In an electric-resistance furnace, the combination with a furnace chamber and a carbonaceous resistor therein, of means for intermittently injecting a predetermined quantity of hydrocarbon oil into said chamber, the quantity and initial velocity of said oil being sufiicient to substantially prevent volatilization thereof until it has reached substantially the center of the chamber.

10. In an electric-resistance furnace, the combination withua plurality of walls spaced apart to form a furnace chamber and a carbonaceous resistor therein, of means for intermittently forcing a predetermined quantity of hydrocarbon oil into said chamber at a predetermined point of entry, the point of entry, quantity and initial velocity of said oil being such as to substantially prevent volatilization thereof until it has reached substantially the center of the chamber.

11. In an electric-resistance furnace, the combination with a plurality of walls spaced apart to form a furnace chamber and a carbonaceous resistor therein, of means for intermittently forcing a predetermined quantity of hydrocarbon oil in a predetermined direction into said chamber at a predetermined point of entry, the point of entry, quantity, direction and initial velocity of said oil being such as to substantially pre- Vent volatilization thereof until it has reached substantially the center of the chamber.

In testimony whereof, I have hereunto subscribed my name this 11th day of April, 1921.

GEORGE M. LITTLE. 

